Forage choppers are agricultural harvesting machines that pick up crop from a field, chop it and transfer it to a transport vehicle via an ejection pipe. The crop can consist of plants such as corn or grain still standing on the field, or of already cut plants gathered into a swath, particularly grass, and is generally used as animal feed or for generating biogas. The cutting process takes place by means of a rotating chopper drum with a plurality of cutters distributed about its circumference, which comminute the crop in cooperation with a shear bar.
The cutters are subject to considerable wear during operation, caused by the crop and impurities contained therein such as sand. Conveyor paddles for crop accelerators and conveyor bars for intake rollers are exposed to similar wear.
To extend the service life of the cutters, they have been equipped in the prior art with hard material coatings, which are applied by hardening, welding or other bonding methods to the surface of the knife that forms the cutting edge (cf. GB 1 332 013 A, EP 2 329 705 A1). The fixation of the hard material layer on the body of the cutter is thus based only on a material bond, which is not always sufficient under high stresses to retain the hard material layer strongly enough on the body. Thus there are occasionally more or less extensive detachments of the hard material coating, which reduces the service life of the cutters.
Embedding a cutting element between two cutter carriers for a straw chopper cutter of a combine (EP 1 935 231 A1) or providing a corresponding arrangement on a lawnmower cutter (U.S. Pat. No. 3,975,891 A) have also been proposed. Such cutters are not suitable for forage harvesters, because the cutting edge of the cutter must move very closely past a shear bar, which is not possible for a cutter element arranged between cutter carriers. The same applies to the above-mentioned conveyor paddles for accelerators and conveyor bars for intake rollers because they convey the crop with their leading surfaces, which is not possible with elements embedded between carriers.
Forage harvester shear bars with beveled corners have also been described, in which hard material inserts of tool steel are mounted by arc welding (cf. the prior art mentioned in EP 1 264 535 A1). It has also been proposed to form an axial recess in the body of the shear bar, into which a mounting is bolted, which in turn has an axial groove into which are inserted wear-resistant inserts made of sintered hard metal that form the shear bar edge (EP 0 761 089 A1). The hard material inserts are wedge-shaped with thicker ends at a distance from the shear bar edge and are fixed on the body of the shear bar by the bolts and the mount. The shear bars are fixed stationarily on the frame of the forage harvester and are substantially thicker than cutters, conveyor paddles or conveyor bars, so that easy transfer of this arrangement to the latter elements is not possible.
One problem addressed by the disclosure is considered to be that of providing a crop processing and/or conveying element for a forage harvester that is movable in operation and does not have the above-mentioned disadvantages or has them to a reduced extent.